class Tuozhuai{
			constructor(box){
				this.oBox = document.getElementById(box);
				this.x = 0;
				this.y = 0;
				this.move();
			}
			move(){
				var _this = this
				this.oBox.onmousedown = function(ev){
					var ev = ev||event;
					var oBorder = document.createElement("div");
					oBorder.style.width = "94px";
					oBorder.style.height = "94px";
					oBorder.style.border = "dashed 3px purple";
					oBorder.style.position = "absolute";
					oBorder.style.left = _this.x+"px";
					oBorder.style.top = _this.y+"px";
					document.body.appendChild(oBorder);
					var left = ev.clientX-_this.oBox.offsetLeft;
					var top = ev.clientY-_this.oBox.offsetTop;
					document.onmousemove = function(ev){
						var ev = ev||event;
						_this.x = ev.clientX-left;
						_this.y = ev.clientY-top;
						oBorder.style.left = _this.x+"px";
						oBorder.style.top = _this.y+"px";
					};
					document.onmouseup = function(){
						_this.oBox.style.left = _this.x+"px";
						_this.oBox.style.top = _this.y+"px";
						document.body.removeChild(oBorder);
						document.onmousemove = null;
						document.onmouseup = null;
					};
					return false;
				};
			}
		}
		window.onload = function(){
			new Tuozhuai("box")
	};